Lack of water flow. Bad water pump or perhaps the lower radiator hose is collapsing (needs a spring).
The radiator is obviously doing it's job based on temps at the top vs temps at the bottom.
Look at the 185 degree reading at where the lower hose enters the water pump. That cooler water is not getting circulated well enough. Either it's a cheap, weak cast impeller, you have way too much clearance between the impeller and the divider plates, or the lower hose is collapsing.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
